even 4000mhz ddr4 still only hits about 35.5gbps
but the actual bottleneck is whatever you're using to connect said 91gbps connection to your pc, 10gbps fibre ports are a thing, maybe several cards with dual ports running together could run over 35.5gbps to saturate your ram

but then you have to move all that to some other drive anyway, unless you want to hold the entirety of GTA V in ram, which i dont think actually performs too significantly better anyway due to how ram works

So say you have two machines, both have 128gb of ram, multiple high end fibre cards, and one has GTA V on it. You can download it from the other machine to your machine from ram and to ram in about 2 seconds.

But you cant download like that from anywhere else, since valve doesnt have servers that do over 35.5gbps speeds, you're still limited by the physical hardware between you and the servers you're accessing.

What i think the original post is reference to, is the in-house data transfer speeds that NASA has. Multiple 10gbps connections can totally give you speeds like this. But theyre not going to be browsing youtube and buffering 4k videos instantly.

If you are comparing to a m.2 ssd you would want to prioritize lower CAS timings on your ram over mhz to gain an advantage, the only game i know offhand that definitely benefits from fast ram or a ramdisk is fallout 4